The bio-diesel process converts fats and oils into diesel. This process includes two reactions in which the feedstock is esterified with methanol to form methyl esters of 16 to 18 carbons in length. The feedstock can include free fatty acids and triglycerides with small amounts of impurities. The purified methyl esters can be used as diesel fuel. Glycerol is formed as a byproduct of this process.
One technique for transesterification of FFAs and triglycerides includes a batch process. The batch process includes a two-phase liquid reaction. The two-phase liquid reaction results in long residence times and low yields. Consequently, batch reactors need to be run at high impeller intensity, high temperature, and high pressure to obtain reasonable reaction rates and yields.
Under atmospheric conditions, the transesterification reaction can require many hours to proceed. A co-solvent such as tetrahydrofuran (THF) can be added to the system to substantially reduce the reaction time by changing the two-phase liquid system into a single-phase liquid.
Other problems for bio-diesel production have a variety of, such as long fluid hold up times, energy intensive separations, and safety concerns over the use of co-solvents.
What is needed is a transesterification process that avoids at least some of the problems of the prior art.